/Engine/Source/Runtime/Engine/Public/BoneContainer.h
This is a native transient structure. Used to store virtual bone mappings for compact poses
struct FVirtualBoneCompactPoseData
FCompactPoseBon...
SourceIndex
Indexof source bone
FCompactPoseBon...
TargetIndex
Indexof target bone
FCompactPoseBon...
VBIndex
Indexof this virtual bone